Abstract: This work introduces a novel access control solution for wireless network services in Internet of Things scenarios. We focus on a minimal use of computation, energy and storage resources at wireless sensors so as to address constrained devices: the proposed methods for key distribution and access control rely on extremely fast key derivation functions and, for the same reason, memory usage is reduced since keys are computed on the fly when needed. Our solution achieves privacy, authentication, semantic security, low energy, low computational demand and impacts mitigation of compromised devices on a simple manner. The access control provided is based on user identity and time intervals. We discuss these properties, compare our proposal to previous related work and provide experimental results that confirm its viability.